Thank you all for your input. Here are some updates/replies based on what was suggested:
JRising wrote:The knock after tamping. Do you mean you're banging the portafilter on the counter after tamping?
Slight nudge on the side of the pf with the tamper to disloge any untamped grinds. Since I switched over to the VST basket (used to have an OEM 18g rancilio one just a week ago) I haven't seen that much channeling.
JRising wrote:And you probably have tried the simplest dialing in method of intentionally grinding too fine so that you ensure that it completely chokes off all flow[...]
Didn't do this as I'm worried about the machine sucking up grinds as part of the choke (I recall reading about it many years back). Is this not a concern?
JRising wrote:Don't be hard on yourself, if you get a lot of great espresso out of it, you're probably not doing anything wrong.
That's the issue though, what I'm getting isn't even good
Borderline undrinkable. I don't even need great, just good would do.
tracer bullet wrote:I'd try a touch less coffee or buy a bigger basket if your'e seeing an imprint of the screen above.
I have to go down to a 13-14g grind to do that. I think I will have to follow Espresso_Junky
's suggestion below to get rid of the screw imprint.
tracer bullet wrote:Give a visual check to be sure the screen isn't filthy on the backside and causing water to come out unevenly.
tracer bullet wrote:Consider a needle of some sort to stir the grinds around to level them out and skip the whacking. [...]
Don't discount the coffee itself either, make sure it's not too old and if needed just move on to a new bag.
Trying the needle method now with a new bag of beans.
Jasper_8137 wrote:Maybe a grinder issue. I really struggled with my Rocky[...]
Absolute worst case scenario... I really don't want to spend on a new grinder.
I have yet to see a fractured puck but at this point I'm happy to try anything. And to be fair, since I switched over to the VST basket (used to have an OEM 18g rancilio one before) I haven't seen much channeling.
Espresso_Junky wrote:Don't be afraid to grind finer as some coffees depending on origin/roast level/age post roast need to be coarser/finer at times. Numbers on a grinder are just for reference.
I'm starting to think the rocky is the issue and that saddens me greatly. I'm now grinding at just a couple of steps past true zero and the flow is still too rapid. I disassemble and clean the grinder once or twice a year at most since I probably do 1lb of coffee every 2 weeks.